Over one million persons in the United States are aphasic subsequent to a stroke. Most of the individuals improve through spontaneous recovery and treatment. However, there are no precise methods for predicting which patients will improve and, for those who do, how much improvement will occur. There is a need to improve prognostic precision in aphasia. Currently employed prognostic methods miss improvement levels by substantial margins. Prognostic information could have a great economic and social impact on patients, their families, and their treatment.